﻿using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace Helpers
{
    public class FileOrStream
    {
        /* - - - - - - - - - - - - - - - - - - - - - - - -  
 * Stream 和 byte[] 之间的转换 
 * - - - - - - - - - - - - - - - - - - - - - - - */
        /// <summary> 
        /// 将 Stream 转成 byte[] 
        /// </summary> 
        public static byte[] StreamToBytes(Stream stream)
        {
            byte[] bytes = new byte[stream.Length];
            stream.Read(bytes, 0, bytes.Length);

            // 设置当前流的位置为流的开始 
            stream.Seek(0, SeekOrigin.Begin);
            return bytes;
        }

        /// <summary> 
        /// 将 byte[] 转成 Stream 
        /// </summary> 
        public static Stream BytesToStream(byte[] bytes)
        {
            Stream stream = new MemoryStream(bytes);
            return stream;
        }


        /* - - - - - - - - - - - - - - - - - - - - - - - -  
         * Stream 和 文件之间的转换 
         * - - - - - - - - - - - - - - - - - - - - - - - */
        /// <summary> 
        /// 将 Stream 写入文件 
        /// </summary> 
        public static void StreamToFile(Stream stream, string fileName)
        {
            // 把 Stream 转换成 byte[] 
            byte[] bytes = new byte[stream.Length];
            stream.Read(bytes, 0, bytes.Length);
            // 设置当前流的位置为流的开始 
            stream.Seek(0, SeekOrigin.Begin);

            // 把 byte[] 写入文件 
            FileStream fs = new FileStream(fileName, FileMode.Create);
            BinaryWriter bw = new BinaryWriter(fs);
            bw.Write(bytes);
            bw.Close();
            fs.Close();
        }

        /// <summary> 
        /// 从文件读取 Stream 
        /// </summary> 
        public static Stream FileToStream(string fileName)
        {
            // 打开文件 
            FileStream fileStream = new FileStream(fileName, FileMode.Open, FileAccess.Read, FileShare.Read);
            // 读取文件的 byte[] 
            byte[] bytes = new byte[fileStream.Length];
            fileStream.Read(bytes, 0, bytes.Length);
            fileStream.Close();
            // 把 byte[] 转换成 Stream 
            Stream stream = new MemoryStream(bytes);
            return stream;
        }

        public static byte[] ReadFully(Stream stream)
        {
            // 初始化一个32k的缓存 
            byte[] buffer = new byte[32768];
            using (MemoryStream ms = new MemoryStream())
            { //返回结果后会自动回收调用该对象的Dispose方法释放内存 
                // 不停的读取 
                while (true)
                {
                    int read = stream.Read(buffer, 0, buffer.Length);
                    // 直到读取完最后的3M数据就可以返回结果了 
                    if (read <= 0)
                        return ms.ToArray();
                    ms.Write(buffer, 0, read);
                }
            }
        }
    }
}
